Medico- Legal Application of RiencWs Test for Arsenic. 243 



A certain number of copper strips will be thus obtained, coated 

 with arsenic, and the next step is to remove from them any sub- 

 stances which may interfere with the second part of the process* 

 Water, oleaginous matters, and solid particles from the solution 

 adhering to the copper, are all to be removed. The first can be 

 easily effected by bringing the metal into contact with bibulous 

 paper, and then warming it gently. The other substances must 

 be cleared off by introducing the strips into some warm water in 

 a capsule, and moving the vessel so as to communicate a gentle 

 motion to them ; friction should be avoided. The cleaning may 

 be continued in three changes of water, and the copper should be 

 afterwards dried as already directed. It is of considerable impor- 

 tance that no empyreumatic vapor should be produced during the 



second stage of the manipulation. l% 



2. The sublimation requires to be conducted with great nicety, 

 when the quantity of poison is minute. The tube used should 

 be about six inches long, and open at both ends, one of which is 

 drawn out to a perforated point. The diameter must be dimin- 

 ished with the amount of metal collected ; when that is very 

 small it should not exceed one tenth of an inch, and never be 

 larger than is necessary, and as small as possible to operate with. 

 The strips used in delicate investigations will therefore be redu- 

 ced in size so as to enter the subliming tube. The greatest at- 

 tention must be bestowed to cleaning the tube thoroughly ; a 

 piece of rag, attached to a wire, should be introduced, and drawn 

 up and down until all dust is removed ; the outside should also 

 be examined, so that it may be perfectly transparent. It must be 

 dried by being warmed over the flame of a spirit lamp. 1 



The copper strips, or as many as may be desired, are then to 

 be introduced into the tube, so as to fill up the narrow end for 

 about two inches. They must not be packed together, for it is 

 necessary that air should pass freely amongst the pieces. The 

 tube is next to be warmed up to the boiling point of water, so 

 that any moisture that may still be present shall be driven off. 

 The heat should be first applied at the occupied end, and the 

 water as it condenses be heated so as to leave the tube entirely. 

 If the condensing fluid be discolored by the presence of empy- 

 reumatic matters, this part of the process must be managed with 

 great care, so that the copper be not subjected to too high a tem- 

 perature. All moisture having been expelled, the tube is to be 



